The inheritance of volatile phenylpropenes in bitter fennel (Foeniculum vulgare Mill. var. vulgare, Apiaceae) chemotypes and their distribution within the plant

The volatile phenylpropenes estragole and t-anethole are the major constituents of the oleoresin of the aerial parts of bitter fennel (Foeniculum vulgare Mill. var. vulgare, Apiaceae). The levels of estragole and t-anethole varied during plant development, being maximal in flowers and developing mericarps. Still the ratio between estragole and t-anethole remained constant throughout development. Estragole-rich types were hybridized with t-anethole rich types to examine the genetic basis of this polymorphism. A reverse correlation between estragole and t-anethole content was evident and the action of a biallelic gene with partial dominance for high estragole content was inferred. Understanding phenylpropene inheritance might explain chemical polymorphism in wild bitter fennel populations, sheds light on the molecular mechanisms that lead to chemotypes evolution and is crucial for breeding fennel varieties with desired chemical compositions.